Automatic slot sealing system for continuous furnaces

ABSTRACT

An automatic, continuously self-sealing device for preventing heat loss from a continuous heat treating furnace, through the slot therein which accommodates a continuous conveyor for supporting and carrying ware through said furnace.

United States atent 1 1 [111 3,718,320 Jespers 1 Feb. 27, 1973 AUTOMATFC SLOT SEALING SYSTEM [56] References Cited FOR CONTINUOUS FURNACES UNITED STATES PATENTS [75] Inventor: Gerard P. Jespers, Dusseldorf.

Germany 1,870,080 8/1932 Woodson ..263/8 R 1,960,808 5/1934 Cope ..263/8 R Assignee: Ferro Corporation, Cleveland 2,272,966 2/1942 Dany R Ohio Primary ExaminerJohn J. Camby [22] June 1971 AttorneyMi1ton L. Simmons [21] Appl. No.: 151,876

Related U.S. Application Data [57] ABSTRACT [63] continuatiomimpart of Sen N0. 26 518 April 8 An automatic, continuously self-sealing device for 1970, abandoned. preventing heat loss from a continuous heat treating furnace, through the slot therein which accommodates [52] US. Cl. ..263/8 R, 34/242 a continuous conveyor for supporting and carrying [51] Int. Cl ..F27b 9/24 r gh sai furn c [58] Field of Search ..26/8 R; 34/242 5 Claims, 8 Drawing Figures PATENTEDFEBZTIBTK SHEET 10F 6 ll-Ill. N Mw INVENTOR GERARD J. ifSPERS 1i 3., 2 4 V M as \u 5 I 2 MI ii. n II. lam m1 wml fi Inn a:

ATTORNEYS PATENTED FEB 2 71973 SHEET 2 OF 6 INVENTQR GERARD J. JE ERS ATTORNEYS PATENTH] FEB 2 71373 SHEET 3 OF 6 PATENTEDFEBZYIHH SHEET 5 OF 6 ATTORNEY PATENTED 3,718,320

sum 5 or e INVENTOR GERARD P. JESPERS AUTOMATIC SLOT SEALING SYSTEM FOR CONTINUOUS FURNACES This application is a continuation-in-part of copending United States application, Ser. No. 26,5l8 filed Apr. 8, I970, now abandoned.

For many years it has been known, in connection with continuous furnaces for porcelain enameling, to provide a slot, particularly in the roof, through which continuous conveyor supporting rods suspend, which rods in turn carry tooling adapted to support and move ware to be heat treated through said furnace.

Because of the extremely high temperatures achieved within the furnace itself, ranging anywhere from 900 to l800F., the running and drive gear for the conveying system is supported outside and above the furnace for heat protection, effecting movement of the ware through the interior of the hot furnace via said support rods.

Two problems have heretofore been associated with this type of furnace in the past, namely, heat loss from the furnace through the support rod slot, and particles of dirt and other foreign material dropping downwardly through said slot into the furnace atmosphere, subsequently onto the vitreous enameled ware during firing thereof, causing undesirable surface defects on such enameled articles.

In order to minimize the problems of heat loss and dirt contamination, a number of sliding seals have been proposed previously, such as shoe plates carried by supporting rods in sliding, overlapping relationship with respect to said slot.

In this respect, see US. Pat. No. 2,272,966.

However, as will be seen from the foregoing U.S.

patent, in order to make absolutely certain that the slot is effectively and continuously sealed, it has been felt necessary to provide shoe plates, not only for the length of the furnace slot itself, but for the entire conveyor length disposed outside the furnace.

Because it is much more efficient to utilize the furnace conveyor for temporary storage, as well as conveying the enameled ware to various stations for assembly, packaging or further processing, thereby eliminating a transfer step from the furnace conveyor to a second conveyor system, it would be most desirable to have the furnace conveyor run directly from the furnace to various subsequent stations, particularly from one floor level to another.

However, with the shoe plates heretofore utilized, whereby they were fixed to the conveyor supporting rods, relatively sharp, flat curves were impossible as far too much space is required if the shoe plates are retained. Too, the added weight, and expense, of heat resistant shoe plates being dispersed throughout an enameling plant on a conveyor chain, makes impractical the use of a lengthened furnace conveyor chain for anything other than the limited purpose of conveying ware through the furnace on a relatively short conveyor circuit.

Another disadvantage to utilizing a furnace conveyor chain, with shoe plates attached thereto, for purposes other than conveying ware through an enameling furnace, is that it is not feasible to use the free car concept, whereby a series of conveyor support rods can be uncoupled from the primary drive chain. This for the reason there is no convenient way to readily disconnect a support rod from a shoe plate, and all support rods would be linked by their overlapping shoe plates, and impractical to detach temporarily.

It is therefore an object of this invention to provide an inexpensive and efficient means for effectively providing a slot seal for a continuous furnace conveyor, at the same time enabling said conveyor to be used for purposes other than strictly the conveyance of ware to be heat treated through a furnace.

It is another object of this invention to provide an effective and efficient slot sealing system for continuous furnaces.

Briefly stated, the shoe plates of this invention are adapted to move synchronously with their ware supporting rods, by providing a notch in said plates, whereby they follow an independent, though overlapping, endless track, automatically sliding into the path of travel of the supporting rods, moving with them along and over the slot thereby sealing same, and automatically disengaging from the supporting rods and their path of travel, returning to the initial point of engagement to complete the cycle.

In this manner, the sealing system may be confined substantially to the furnace proper while the conveyor, after it has passed through the exit point of said furnace, may, free of the shoe plates, be carried to any point away from the furnace, at any level, unrestricted by the shoe plates, which are left back at the furnace, to continue to perform their function.

In the attached drawings,

FIG. 1 is a plan view ofa closed, endless circuit of the shoe plates of this invention.

FIG. 2 is a cross section of a portion of a furnace roof, the conveyor and the sealing system, taken along the line 1111 in FIG. 1.

FIG. 3 is a section of the overlapping portions of two shoe plates taken along the line III-III in FIG. 1.

FIG. 4 is a perspective view of elevating guide bars for locating sealing disks.

FIG. 5 is a schematic view of the synchronous drive of the shoe plates of this invention.

FIG. 6 is a schematic plan view of a variant form of this invention.

FIG. 7 is a cross section on the line VIIVII of FIG. 6.

FIG. 8 is a cross section on the line VIIIVIII of FIG. 6.

For an understanding of the function of this invention, referring to FIGS. 1 and 2, the system comprises an endless conveyor chain 2, which is linked to a number of vertical connecting members 14. The upper portion of members 14 is movably suspended, by means of trolleys, from an endless, oval horizontal track 16, the members 14 following oval path 8 as a consequence of movement of said endless chain.

As will be seen from reference to FIG. 3, the lower, threaded, extremity of members 14 is provided with appropriate nut means 33 maintained in position by suitable cotter means 26, said nut means spaced from shoe plate I by washer 15.

As will be seen then, connecting members 14 guide and carry shoe plates 1 around the endless circuit described by oval track 8, as shown in FIG. 1.

As will be seen from FIGS. 1 and 3, there is an offset overlapof two successive shoe plates 1, at which point the front end of one shoe plate, and the rear end of the succeeding one, both rest in overlapping relationship, supported by washer vertical means 14 in effect supporting, moving and maintaining said shoe plates in their relative position via a suitable hole through said shoe plates, through which member 14 passes.

In this way, the shoe plates may pivot, within the confines of their path of movement, freely with respect to each other, and the member 14.

In order to maintain the shoe plates longitudinally in a horizontal plane as much as possible, a step 24 is provided at the end of each shoe plate, the step height being the thickness of the shoe plate. The opening provided in the lower overlapping shoe plate may assume an oval configuration so as to minimize binding between the member 14 and the shoe plates.

From FIGS. 1 and 2 it will be seen that one straight leg of the oval path 8 followed by the shoe plates may be caused to pass over and coincide with a slot 11 in a plane 25. Plane 25 being the roof of a heat treating furnace, or similar installation, having a chamber which is to be sealed. The slot 11 extends generally the entire length of the furnace, and is provided with suitable shoe plate tracks 6 coinciding with plane 25, shoe plates 1 passing in substantially snug, sliding relationship over said tracks to thereby effectively seal the slot 1 l.

Inclined ramp means, 28, is provided just anterior the point where said shoe plates commence their slot scaling function, to smoothly guide successive shoe plates onto track 6, disposed on either side of said slot.

Optionally, the shoe plates 1 may be supported solely by vertical members 14 along that portion of oval track 8 during which they are not supported by slot tracks 6, or idler support tracks 31 may be provided if desired.

The ware to be fired or heat treated in the furnace is suspended from supporting rods 4, usually via suitable tooling fixed to the lower extremity thereof, as shown in FIG. 2. Support rods 4 are each suspended from trolley 5, which may be, in turn, coupled directly to a conveyor chain movable along track 20. Optionally, and particularly as shown in FIG. 2, utilizing the free car" concept, by means of a main conveyor trolley device 27, at an appropriate break, or switch in lower track 20, a series of support rods 4 may be shunted and diverted from the path followed by principal trolley 27.

As will be seen from FIGS. 1 and 4, the supporting rods 4 must fit between two successive shoe plates 1 as the rod passes through slot 11. In order to accommodate said supporting rod 4, suitable notches 34 are provided by appropriately beveling the respective leading and trailing corners of two successive, overlapping shoe plates.

As will be readily apparent, depending uponthe length of the shoe plates, and the space between successive supporting rods 4, one or more intervening shoe plates may be utilized, and in which the notch has been omitted.

From FIGS. 1 and 4, it will be seen that the slight gap resulting from circular support rod 4 passing through the V-shaped opening formed by notches 34 may be effectively sealed by supplemental sealing disks 12, which are carried on support 9 on said supporting rods.

Support 9 may be in the form of a roller bearing, which serves to guide the supporting rod 4 through the slot 11; in this manner, if the supporting rod 4 is not hanging vertically, the rollable support 9 rolls along one of the slot walls, thereby rollably spacing support 9 from physical contact with said slot wall as it passes through the furnace. Rotatable support 9 may rest on collar 10, firmly fixed to support rod 14.

As will be seen from FIG. 4, inclined ramp means 13 are provided to lift sealing disks l2, slidably supported on support rod 4, away from the roller 9, said inclined ramp means 13 terminating at a point where the supporting rod 4 has already been positioned within the notch between two overlapping shoe plates 1, permitting sealing disk 12 to drop onto the top overlapping shoe plate, thereby sealing off said V-shaped gap during support rod 4's passage through the furnace.

Obviously, for most effective sealing, the straight leg of oval circuit 8 should extend slightly beyond the slot at both ends.

As will be apparent, shoe plates 1 must move synchronously with support rods 4. Any number of well known, conventional means may be employed to achieve such synchronization, one of which is depicted in FIG. 5. Chain 17, rotatable about sprockets l8, has

driving lugs thereon meshable with the links of the power chain 3, carrying supporting rods 4. The sprocket wheels 18 are each connected by shaft 19 to sprockets 30, which are rotated synchronously by the power chain 3, via chain 17 and sprockets 18. Sprockets 30 may then be utilized to drive a meshed chain 2 for the shoe plates 1 directly, or through chain 29, fitted with driving lugs.

As is well known, roof 25 of the furnace may be supported by the column and cross member combination 22 and 23 respectively, from which tracks 16, 21 and 20 may be also supported.

A variant form of this invention contemplates means whereby each opening can be sealed off by a flap, which is attached in a pivoting manner to one of the shoe plates which forms this opening.

By preference each flap is provided with a guiding device which cooperates with a guide rail in such a manner, that prior to the point where the shoe plates and the supporting rods join each other, the flap is.

swung aside from the opening so that the latter is free to receive a supporting rod.

In addition, each flap may be provided with a downward projecting rim which cooperates with a shoe plate track along the slot in such a way that in the absence of a drop rod the flap is swung into a sealing position of the opening.

These and other characteristics of the proposed sealing installation are explained in the following description of an application example as shown in the attached drawing. In this description similar parts with same reference numbers are used as those in the Dutch patent application 69.05.436.

Referring to FIG. 6, supporting rods are moved by a supporting rod conveyor along a track 40 from right to left, during which each supporting rod moves into the simultaneous positions 4a, 4b, 4c, 4d and 4e and afterward through a slot 11 into the roof of for instance a furnace 7.

The endless chain of shoe plate conveyors moves rods 14 along an endless oval track 8. The rods support shoe plates 1 and move into the positions 14a up to and including 14e, which belong to the positions 4a up to and including 4e of the supporting rods, whereby the shoe plates can move into the positions la up to and in cluding 1e.

The shoe plates 1 seal off the slot 11 in the roof of furnace 7 during the movement of the rods 14 along the section of track 8 running parallel to the slot 1 1. By this sealing method a minimum of heat is lost from the fur nace. In order to be able to move the supporting rods 4 through the slot some of the shoe plates are provided with cut outs 34, whereby two following shoe plates with cut outs provide an opening over the slot. A suspension rod can extend through via an opening 35 into the slot 11. It is noted that each following pair of shoe plates does not have to form an opening, but that the number of formed openings depends upon the distance between two successive suspension rods if no suspension rod in between has been uncoupled.

In order to seal off an opening 35 in the absence of suspension rod 4, on one of each pair of adjacent shoe plates with cut outs a pivoting flap 41 is provided. In the left bottom corner of FIG. 1 a flap is shown in the position, whereby this flap seals off the opening 35 as formed by the shoe plates 1.

Such a flap 41 may be attached onto a shoe plate 1 in any pivoting manner. According to FIGS. 6 and 7 the flap 41 can pivot on a rod 14, whereby the same rod serves at the same time to support two adjacent shoe plates. Each flap is provided with a lip 42 which cooperates with a rail in order to bring back the flap from an open position into the position to seal the opening 35. The shoe plate 6 track along the slot 11 may serve as a rail, whereby the lip 42 has been bent downwards to such an extent that between the flap 41 and the upper shoe plate 1 a slotted space remains open. As therefore the flap does not rest on the upper shoe plate the same can easily pivot. The flap rests with enough force on the shoe plate track by the eccentric position from the pivot point on rod 14.

For pivoting into the opened position each flap is provided with a guiding device 43, which is pushed aside by a guide rail 44 as is shown in FIGS. 6 and 8. Each flap is pivoted aside via the apertaining guiding device 43 prior to the place where the shoe plates 1 and the shoe plates 4 join each other so that the opening 35 formed by the cut outs 34 in the adjacent shoe plates is opened to receive a supporting rod 4. For example, the flap 41a has been pivoted sidewards by the apertaining guiding device 43a and in position b this is still the case for the flap 4117. In the position c the supporting rod 4c has moved into a cut out 45 of the flap 41c and in the position d the supporting rod 4d locks the flap 41d via the cut out. In the position e the supporting rod 4e is already inside the cutouts 34 of the shoe plates 1 and the flap 41 e maintains in the open position via the cut out 452 of the flap. The supporting rod can now be moved through the slot 11.

If no supporting rod 4 has been enclosed in the cut outs 34 of the shoe plates, the flap will be pivoted back into the position to seal the opening 35 as the lip 42 comes to rest onto the shoe plate track along the slot 11. This pivoting back of the flap is only resisted by the supporting rod 4 if present.

The guiding device 43 may consist ofa roller 46 on a shaft 47 as is shown in FIG. 8.

In order to enhance slidability, the front edge 48 of the lip 42 as seen in the direction of travel is bent upwards.

The length of the flap as seen in the direction of travel is preferably such, that the flap touches the next adjacent rod 14 after having sealed opening 35.

I claim:

1. In the combination of a slot seal and ware support apparatus for a furnace having a slot extending through the roof thereof, including refractory members defining the edges of said slot, shoe plate support members disposed thereabove and extending parallel to said slot on each side thereof, a plurality of work supporting bars with means for suspending and moving said bars through said slot, a plurality of overlapping, articulated shoe plates arranged in a closed endless circuit in a plane substantially parallel to the plane of said slot, a segment of said closed shoe plate circuit disposed to substantially coincide with said slot, means for passing said shoe plates over said shoe plate support members and over said slot synchronously with said support bars, said closed shoe plate circuit disposed to converge and coincide with the line of travel of said support bars just anterior the commencement of their entry into said slot, and to diverge and separate therefrom just posterior thereof.

2. The improvement of claim 1 wherein said work supporting bars have a flat longitudinally slidable overlapping member supported by a fixed collar, ramp means for elevating said slidable member just anterior the point of convergence of the line of travel of said support bar with the closed circuit of said shoe plates, openings in said shoe plates adaptable to receive therewithin said supporting bars, said ramp means terminating at a point subsequent to where a supporting bar has been embraced by said opening, for permitting said slidable member to descend and be supported by an overlapping shoe plate as a secondary seal.

3. The improvement of claim 1 wherein said work supporting bars have a flat, longitudinally slidable overlapping member supported by a fixed collar, ramp means for elevating said slidable member just anterior the point of convergence of the line of travel of said support bar with the closed circuit of said shoe plates, openings in said shoe plates adaptable to receive therewithin said supporting bars, said ramp means terminating at a point subsequent to where a supporting bar has been embraced by said opening for permitting said slidable member to descend and be supported by an overlapping shoe plate as a secondary seal, said opening in said shoe plates is V-shaped when said shoe plates are aligned with said slot, and the means for moving said supporting bars is a conveyor power chain meshably connected with a secondary chain and sprocket means for synchronously moving said shoe plate members. i

4. The improvement of claim 1 wherein said work supporting bars have a flat, longitudinally slidable overlapping member supported by a fixed collar, ramp means for elevating said slidable member just anterior the point of convergence of the line of travel of said support bar with the closed circuit of said shoe plates, openings in said shoe plates adaptable to receive therewithin said supporting bars, said ramp means ter minating at a point subsequent to where a supporting bar has been embraced by said opening for permitting said slidable member to descend and be supported by an overlapping shoe plate as a secondary seal, said opening in said shoe plates is V-shaped when said shoe plates are aligned with said slot, and the means for moving said supporting bars is a conveyor power chain meshably connected with a secondary chain and sprocket means for synchronously moving said shoe plate members, and said support bar has roller means disposed thereon at a level within the upper and lower limits of said slot for maintaining said support bars substantially centrally within said slot during their travel therethrough.

5. The apparatus of claim 1 wherein the means for passing shoe plates synchronously with said support bars is a notch between the leading and trailing ends, respectively, of two successive shoe plates, said notch formed by complimentary beveled cuts, respectively,

on each said leading and trailing ends, heat sealing means for reducing heat loss through said notch comprising sealing plate members disposed atop said shoe plates, pivotably mounted adjacent the inner edge of a leading shoe plate, said sealing plate member having a downwardly projecting skid along its outer periphery slidably engaging a refractory slot member for frictionally urging the trailing end of said sealingplate inwardly over said notch, said sealing plate member having a support bar gap in the trailing edge thereof for accommodating and embracing a support bar and coacting with said notch to form a heat seal when a support bar is embraced by said notch and said gap, cam follower means on said sealing plate member, and cam means disposed to coact therewith for pivoting said sealing plate to an open position whereat its gap is in a position to engage a converging support bar. 

1. In the combination of a slot seal and ware support apparatus for a furnace having a slot extending through the roof thereof, including refractory members defining the edges of said slot, shoe plate support members disposed thereabove and extending parallel to said slot on each side thereof, a plurality of work supporting bars with means for suspending and moving said bars through said slot, a plurality of overlapping, articulated shoe plates arranged in a closed endless circuit in a plane substantially parallel to the plane of said slot, a segment of said closed shoe plate circuit disposed to substantially coincide with said slot, means for passing said shoe plates over said shoe plate support members and over said slot synchronously with said support bars, said closed shoe plate circuit disposed to converge and coincide with the line of travel of said support bars just anterior the commencement of their entry into said slot, and to diverge and separate therefrom just posterior thereof.
 2. The improvement of claim 1 wherein said work supporting bars have a flat longitudinally slidable overlapping member supported by a fixed collar, ramp means for elevating said slidable member just anterior the point of convergence of the line of travel of said support bar with the closed circuit of said shoe plates, openings in said shoe plates adaptable to receive therewithin said supporting bars, said ramp means terminating at a point subsequent to where a supporting bar has been embraced by said opening, for permitting said slidable member to descend and be supported by an overlapping shoe plate as a secondary seal.
 3. The improvement of claim 1 wherein said work supporting bars have a flat, longitudinally slidable overlapping member supported by a fixed collar, ramp means for elevating said slidable member just anterior the point of convergence of the line of travel of said support bar with the closed circuit of said shoe plates, openings in said shoe plates adaptable to receive therewithin said supporting bars, said ramp means terminating at a point subsequent to where a supporting bar has been embraced by said opening for permitting said slidable member to descend and be supported by an overlapping shoe plate as a secondary seal, said opening in said shoe plates is V-shaped when said shoe plates are aligned with said slot, and the means for moving said supporting bars is a conveyor power chain meshably connected with a secondary chain and sprockEt means for synchronously moving said shoe plate members.
 4. The improvement of claim 1 wherein said work supporting bars have a flat, longitudinally slidable overlapping member supported by a fixed collar, ramp means for elevating said slidable member just anterior the point of convergence of the line of travel of said support bar with the closed circuit of said shoe plates, openings in said shoe plates adaptable to receive therewithin said supporting bars, said ramp means terminating at a point subsequent to where a supporting bar has been embraced by said opening for permitting said slidable member to descend and be supported by an overlapping shoe plate as a secondary seal, said opening in said shoe plates is V-shaped when said shoe plates are aligned with said slot, and the means for moving said supporting bars is a conveyor power chain meshably connected with a secondary chain and sprocket means for synchronously moving said shoe plate members, and said support bar has roller means disposed thereon at a level within the upper and lower limits of said slot for maintaining said support bars substantially centrally within said slot during their travel therethrough.
 5. The apparatus of claim 1 wherein the means for passing shoe plates synchronously with said support bars is a notch between the leading and trailing ends, respectively, of two successive shoe plates, said notch formed by complimentary beveled cuts, respectively, on each said leading and trailing ends, heat sealing means for reducing heat loss through said notch comprising sealing plate members disposed atop said shoe plates, pivotably mounted adjacent the inner edge of a leading shoe plate, said sealing plate member having a downwardly projecting skid along its outer periphery slidably engaging a refractory slot member for frictionally urging the trailing end of said sealing plate inwardly over said notch, said sealing plate member having a support bar gap in the trailing edge thereof for accommodating and embracing a support bar and coacting with said notch to form a heat seal when a support bar is embraced by said notch and said gap, cam follower means on said sealing plate member, and cam means disposed to coact therewith for pivoting said sealing plate to an open position whereat its gap is in a position to engage a converging support bar. 